Multi-layer bags

ABSTRACT

BY PULLING THE CORD WITHOUT BREAKING AT LEAST THE INNERMOST LAYER.   1. A MULTI-LAYER BAG COMPRISING A PLURALITY OF LAYERS OF BAG FORMING MATERIAL, SAID LAYERS BEING SUPERPOSED RELATIVE TO EACH OTHER TO FORM A FRONT SHEET AND A REAR SHEET, GUSSETS FORMED AT BOTH LONGITUDINAL SIDE EDGES OF SAID BAG BETWEEN SAID FRONT SHEET AND SAID REAR SHEET, THE UPPER EDGES OF AT LEAST SOME OF THE LAYERS BEING DISPLACED IN THE LONGITUDINAL DIRECTION TO DEFINE STEPWISE BONDING MARGINS WHICH ARE FOLDED BACK AND BONDED TO SAID FRONT SHEET SO AS TO SEAL THE MOUTH OF SAID BAG, AND A BAG OPENING CORD DISPOSED ACROSS SAID BAG NEAR SAID MOUTH AND SECURED BETWEEN SAID LAYERS WITH THE OPPOSITE ENDS PROJECTING BEYOND SAID SIDE EDGES, SAID CORD BEING POSITIONED SUCH THAT SAID BAG CAN BE OPENED

Saito Nov. 26, 1974 MULTl-LAYER BAGS [75] Inventor: Akio Saito,Futasegawa-cho,

V Kakegawa-shi, Japan [73 Assignee: Showa Seitai Kogyo Kabushiki Kaisha,Tokyo, Japan [22] Filed: Mar. 11, 1971 [21] Appl. No.: 123,243

[52] U.S. Cl. 229/55, 229/66 [51] Int. Cl B65d 31/02 [58] Field ofSearch 229/55, 66, 86

[56] References Cited UNITED STATES PATENTS 185,727 12/1876 Collins229/86 3,203,620 8/1965 Becker 229/55 UX 3,565,328 2/1971 Hudson 229/553,592,380 7/1971 Gerard 229/55 X FOREIGN PATENTS OR APPLICATIONS 288,1773/1965 Netherlands 229/55 Primary ExaminerDonald F. Norton Attorney,Agent, or FirmWard, McElhannon, Brooks & Fitzpatrick [57] ABSTRACT Amulti-layer bag comprises front and rear sheets each consisting of aplurality of superposed layers of bag blanks, and gussets between frontand rear sheets along the longitudinal side edges. The layers aredisplaced relatively to each other in the longitudinal direction todefine stepwise bonding margins which are folded back and bonded to thefront sheet so as to seal the mouth of the bag. A bag opening cord isdisposed across the bag near the mouth and secured between layers withopposite ends projected beyond side edges. The cord is positioned suchthat the bag can be opened by pulling the cord without breaking at leastthe innermost layer.

4 Claims, 11 Drawing Figures PATENTEL M2619 .SHEET 10F 4 INVENTORATTORNEY PAIENIE RUV26I974 SHEET 2 0F 4 INVENTOR ATTORNEY PAIENIELNBVZSW3.850.366

" saw 30F 4 INVENTOR ATTORNEY PATENTEL 3,850,366

sum #0; 4

INVENTOR ATTORNEY MULTl-LAYER'BAGS BACKGROUND OF THE INVENTION Thisinvention relates to a multi-layer bag having a bag opening cord andmore particularly to an improved multi-layer bag wherein mounting of thecord and the opening of the bag are easy.

A multi-layer bag has been prepared by using a plurality of layers ofbag blanks and by interposing side gussets between front and rear sheetsso that the bag forms a cube when it is filled.

In such a multi-layer bag, in order to form upper and bottom seals theupper and lower edges of the layers comprising the rear sheet areprojected beyond the upper and lower edges of the layers comprising thefront sheet, and the extent of projection is stepwisely increased onboth upper and lower edges from the front layer to the rear layer so asto form a bonding margin .on the upper and lower edges of each layer.Both side gussets are similarly stepped to form bonding margins alongthe side edges of respective layers, then a suitable bonding agent isapplied to respective bonding margins, and the margins of the rear sidesheet are folded back onto the front sheet to complete a bag.

The multi-layer bag of the construction just described is advantageousin that the bonding agent can be applied to all bonding margins in oneprocess step, that folding and bonding operations can be madesimultaneously for all edges thus simplifying the process step, that thestrength of the seals is high and that charging of the content is alsoeasy.

However, this type of multi-layer bag is difficult to open by peelingoff its bonded edges. This not only requires considerable time but alsothe opened edges become irregular thus making it difficult to remove thecontent. Portions of the layers other than the edges that form the mouthof the bag are broken. Further, scraps of the blank which are formedwhen the bag is opened are admixed with the content. This is notdesirable when the content is a raw material of a synthetic resin suchas polyethylene or vinyl chloride.

SUMMARY OF THE INVENTION It is therefore an object of this invention toeliminate various difficulties mentioned above.

Another object is to provide a novel bag including a cord which isdisposed at the seal and across the bag between layers of the bag blankwith both ends projected beyond the side edges of the layers of blank sothat the bag can be readily opened by pulling the cord.

A further object of this invention is to provide a novel multi-layer bagwhich can be opened without breaking at least the innermost layer of thebag by pulling the opening cord.

According to this invention there is provided a multilayer bagcomprising a plurality of layers of a blank, said layers are superposedrelative to each other to form a front sheet and a rear sheet, gussetsformed at both longitudinal side edges of the bag between front and rearsheets, the upper edges of at least some of the layers being displacedin the longitudinal direction to define stepwise bonding margins whichare folded back and bonded to the front sheet so as to seal the mouth ofthe bag, and a bag opening cord disposed across the bag near the mouthand secured between the'layers with the opposite ends projected beyondthe side edges,

the cord being positioned such that the bag can be opened to at leastthe innermost layer.-

BRIEF DESCRIPTION OF THE DRAWINGS The invention can be more fullyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 shows an elevational view of a portion of the mouth of a bagembodying the invention;

FIG. 2 shows a sectional view of the bag taken along a line II II inFIG. 1, with the thickness of the bonding agent 5 exaggerated;

FIG. 3 shows a view similar to FIG. 2 but taken along a line III III inFIG. 1;

FIG. 4 shows a sectional view of the bag after the i mouth has beensealed;

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 to 6of the accompanying drawings, there is shown a bag comprising front andrear sheets A and B each consisting of an inner layer 1, an intermediatelayer 2 and an outer layer 3 made of suitable bag forming material. Itis to be understood that the side edges of respective layers are bondedtogether on front surface to form a tubular body C. Between the frontsheet A and the rear sheet B, each of the layers 1, 2 and 3 is folded atits opposite side edges to form a gusset D of a V-shaped cross-sectionalconfiguration.

At the mouth of the tubular body C, the outer layer 3, the intermediatelayer 2 and the inner layer 1 of the front sheet A are provided withupper edges 3a, 2a and la respectively projecting stepwise in the ordermentioned. The upper edge of the inner layer 1 is provided with asection la and a section la" which projects beyond sections la to theright of a step or border line la positoned to the right of the portionof layer 1 overlapping the gusset D. Although FIG. 1 shows the left handportion of the bag, it is to be understood the right hand portion isalso constructed in the same manner. At the rear sheet B, the upperedges 2b and 3b of the intermediate layer 2 and the outer layer 3,respectively, are projected beyond the central section In" of the upperedge 1a of the inner layer 1 of the front sheet A in the order of edges2b and 3b. The upper edge lb of the inner layer 1 of the rear sheet B isprovided with side sections 1b and a central section 1b on the oppositesides of a step or border line lb and at positions corresponding to theside sections la, border line la' and central section 1a" on the upperedge la of the inner layer 1 of the front sheet A. Side sections lb arepositioned between the central section la" and the upper edge 2b of theintermediate layer 2 whereas the central section lb is between thecentral section 1a" and opposite side sections 1a.

The front side wall D of the gusset D has the same height as the upperedge 1d of the inner layer 1 and both side sections of the upper edge 1aof the inner layer 1 while the upper edges 2d and 3d of the intermediatelayer 2 and outer layer 3 have the same height as the central section1b" of the upper edge lb of the inner layer 1. At the rear side wall D"of the gusset, the upper edges 3d" and 2d" of the outer layer 3 andintermediate layer 2 have the same height as the upper edges 2d and 3dof the front side wall D and the upper edge 1d" of the inner layer 1 hasthe same height as both side sections lb of the upper edge 1b of theinner layer 1 of the rear sheet B.

A bag opening cord 4 is secured between the inner layer 1 and theintermediate layer 2 of the rear sheet B and across the body C of thebag. The opposite ends of this cord 4 are extending outwardly throughnotches formed on the side edges of the intermediate layer 2 and outerlayer 3 of the rear sheet B. The cord 4 is positioned slightly above theupper edge 2a of the intermediate layer 2 of the front sheet.

A plurality of layers comprising the front sheet A are superposedrelative to each other such that portions above both side sections 1a ofthe upper edge 1a of the inner layer 1 are exposed like a step so as toleave exposed bonding margins 11a, 12b, 13b, 12d, 11d" and 11b. Then, asuitable bonding agent 5 is applied onto these exposed bonding margins.Portions of the layers above the upper edge of the intermediate layer 2of the front sheet A are folded back along the upper edge 20 thussealing the mouth of the bag.

Under these conditions the intermediate layer 2 and the outer layer 3 ofthe rear sheet B are positioned outside of cord 4, as shown in FIGS. 4and 6. As shown in FIGS. 6 and 7, at the gusset D, bonding margins 11d",12b, 12d and 13b are bonded to overlay the inner layer 1 so as toprevent the content from leaking through both side corners.

The bonding agent is also applied as dots or lines or stripes betweenthe inner and intermediate layers 1 and 2 and between the intermediateand outer layers 2 and 3. Before insertion, the bag opening cord is alsoapplied with the bonding agent at spaced apart points or along Aftersealing the mouth as above described the bag is placed upside down, andthe content 6 is charged in the bag through its bottom opening which isnow brought to the upper side. The step shaped bonding margins at thebottom edges are bent back to seal the bottom of the bag.

To open the bag which has been sealed as above described, the cord 4 ispulled upwardly as viewed in FIG. 4 to break or tear the intermediatelayer 2 and the outer layer 3 of the rear sheet B which are placed abovecord 4 in the sealed state shown in FIG. 4. Thus, the inner layer 1 isnot broken, but only two layers are required to be broken. Although bothside portions including the gussets are not broken, since the width ofthe gusset is relatively small when compared with the total width of thebag, the content can be taken out readily without any trouble.

In the modified embodiment shown in FIG. 8, insertion of the bag openingcord is made more easy. More particularly, the upper edges of respectivelayers of the front sheet are cut substantially straight andlongitudinal slits 20a, 20b, 20a and 20b are cut through respectivelayers other than the innermost layer at portions near both side edges.The cord 4 is threaded or knitted through these slits with both its endsprojected beyond the side edges of the bag.

With this construction, it is possible to readily secure the cord bymerely threading it through respective layers and since the portion 21of the cord exposed to the outside of the layers are secured to theoutermost layer when the mouth is sealed, the layers can be broken bypulling the cord, and also in the case where the slits of respectivelayers are staggered, as shown in FIG. 8, superposed layers can bebroken successively.

In each of the above described embodiments, if the bonding agent wereapplied to partially close the mouth at both side gussets, the leakageof the content can be prevented effectively. This can be accomplished byapplying the bonding agent (preferably of the thermobonding type) to thehatched areas on the inner surface of the intermediate layer at thegusset, as shown in FIG. 9, thus causing these portions to adhere toadjacent layers by applying heat so as to seal the gusset.

Instead of inserting the bag opening cord between layers of the blank,such cord may be placed between surfaces which are bonded together atthe time of sealing so as to secure the cord by the bonding agent. Sincethe upper edge la of the innermost layer of the front sheet ispositioned above the upper edge 1b" of the rear sheet as shown in FIG. 1and remains without being applied with the bonding agent at the time ofsealing, after opening the mouth by pulling up the cord 4 it is possibleto freely open the upper edge la to remove the content.

FIGS. 10 and 11 respectively corresponding to FIGS. 4 and 5 show themanner of opening of the modified bag. Except for the cord 4, otheraspects are identical to those shown in FIGS. 4 and 5.

While in the illustrated bags, the front and rear sheets consist ofthree layers of blanks, the number of layers of each sheet may beincreased or decreased as desired. Likewise, the construction andarrangement of the stepwise bonding margins can also be modified.However, it is essential that the front and rear sheets of the blankshould not be bonded together at the mouth and that the bag opening cordshould be positioned beneath the upper edge of the innermost layer ofthe rear sheet.

Thus, this invention provides a novel bag which can be opened beryeasily by pulling the bag opening cord to break or tear the layers ofthe blank overlying the cordlln the illustrated embodiments, since thecord is positioned beneath the innermost layer of the front sheet, it ispossible to decrease the number of layers which are required to bebroken. Further, as the cord is positoned at the upper portion of thebag when it is filled with the content and since the number of layers tobe broken is the same at the gussets, the provision of the gussets doesnot render it difficult to open the bag. As above described, since atleast the innermost layer is not broken by the cord scraps of the layersare not admixed with the content when it is taken out. Further, as thebag opening cord is provided across the bag independently of thegussets, the cord can be readily attached.

What is claimed is:

l. A multi-layer bag comprising a plurality of layers of bag formingmaterial, said layers being superposed relative to each other to form afront sheet and a rear sheet, gussets formed at both longitudinal sideedges of said bag between said front sheet and said rear sheet,

the upper edges of at least some of the layers being displaced in thelongitudinal direction to define stepwise bonding margins which arefolded back and bonded to said front sheet so as to seal the mouth ofsaid bag, and a bag opening cord disposed across said bag near saidmouth and secured between said layers with the opposite ends projectingbeyond said side edges, said cord being positioned such that said bagcan be opened by pulling the cord without breaking at least theinnermost layer.

2. The multi-layer bag according to claim 1, wherein respective layersof the front sheet excepting at least the innermost layer are formedwith two longitudinal slits at said mouth and said bag opening cord isthreaded through said slits.

3. The multi-layer bag according to claim 1, wherein said cord issecured between layers which are positioned to the rear of at least theinnermost layer, and

